If explosive propellants are not used for rail guns, why does this image of a railgun being fired show fire? The wikipedia article for railguns clearly states

The absence of explosive propellants or warheads to store and handle, as well as the low cost of projectiles compared to conventional weaponry come as additional advantages.

So, railguns don't require explosives or fire. Then right next to it on the page image, it shows a projectile being launched from a railgun with lots of fire.
What exactly is going on here?

https://en.wikipedia.org/wiki/Railgun#U.S._Navy_tests
 A: This is true that railguns, coilguns, and similar devices using magnetic force as the projectile propulsion in general do not require any explosive propellants.
However it is not true that they do not use it at all.
Consider the most basic railgun*). It consists of a metallic projectile inserted between two conductive rails. Rails are connected to DC power. The metallic projectile touches the rails providing a means of closing the circuit, current flows, and provided it is large enough, the projectile can be repelled outwards from the rails.
But then, if the current is high enough, another thing can also happen: due to the static friction, vibrations, dirt, etc, the metallic projectile may sometimes not gain enough initial velocity, and due to the build up of the heat it can actually weld itself into the rails instead.
This is one of the reasons for why some (if not most) railgun designs actually use an initial pre-acceleration stage that use chemical (or other) propellants to give the projectile some initial velocity at the moment it enters the actual barrel with rails which then accelerates it further into final velocity.
You can see similar additions even in amateur constructions like seen on this video. Here they use CO2 like in airgun, but military constructions use explosive propellants too.
This of course does not deny the fact that even on this amateur video (and its follow ups) you can see the "fire" emerging from the barrel during the shot. They used just CO2, so I'm pretty sure that what you see is the heated metal torn from by the friction between the rails and projectile (one of those videos shows the amount of wear on the rails).
The "fire" here is not that significant as in the photo you provided, though, it's still present. While the military versions that use initial explosive propellants certainly make it much more spectacular.
*) coilguns are usually not affected since the projectile cannot 'weld', but even some coilgun designs use pre-acceleration stages just to make better use of the coil energy. However, I don't know how's that supposed to be better, maybe it's about stationary friction not present when the projectile is already moving out..
